The PC-C36 has a TFX 300W PSU, with a backplate that can be switched between 4 low-profile expantions or 2 full size expantions with riser card.
The PC-C37 can take a full size ATX PSU, with a fixed 4 low-profile expantions.
PC-C36 is at least ~200$ and the PC-C37 is at least ~150$.
They are less than 10cm high, so that's pretty slim, even slimmer than the NSK1480, AND takes a full ATX PSU in the case of PC-C37 (silent 120mm fan hourray!)

I'm wondering what i should get.
A C36, a geforce 8300 board with hybridpower and a 9800GT.
Or a C37 that's 50$ less, and get a DFI matx board that has two x16 PCIe slots and do a 3 way crossfire with 2x low profile HD3450 + IGP, and a silent full ATX PSU. This should be more silent, but i don't think it'll beat the first option for gaming.

For sure the 9800 Gt is enough for gaming and would handle any high definition movies. Not sure for the need of a integrated GPU. Altough if hybrid-sli really work your 9800 gt would only really be used in more graphic intensive task.

What kind of gaming you want to do ? Would make the card selection easier.

300 w is not enough everything + the 9800,

According to BFG you need : 400W with a x6800 quad and at least 26amp on the 12v ramp.

I used the power supply calculator and a 2x HDD, 1x DVDRW, 4x DDR2, a phenom x3 (undervolted) made it at 300W. I also got an athelon x2 5000+ black edition i could use if the phenom eats too much.
I wanted the hybridpower so i could turn off the 9800GT when not needed, it's more a question of silence than anything else.
I'm looking to do some shooters from a year or two back. I'd like to play the upcoming fallout.